永磁同步电机矢量控制中死区补偿技术的研究

本文针对永磁同步电机矢量控制系统,分析了死区电压矢量对三相输出电压的影响以及死区电压矢量与定子电流方向的关系,提出了一种基于SVPWM矢量控制的死区补偿方法。定子电流矢量角根据计算得出,避免了传统方法在相电流过零处由于电流方向检测不准而影响补偿效果。该方案无需增加硬件电路,对软件进行修改即可实现。仿真试验结果证实了该方法的有效性。     

非高斯噪声下的一种自适应IIR滤波算法

给出一种用递归总体最小平均P-范数法来实现IIR滤波器的估计,在估计中采用power迭代法,并应用矩阵求逆引理克服了直接求逆的繁琐计算,在文章的最后给出计算机仿真,显示了该算法性能的优越性。     

Kinetic‐Oriented Construction of MoS2 Synergistic Interface to Boost pH‐Universal Hydrogen Evolution

As a prerequisite for a sustainable energy economy in the future, designing earth‐abundant MoS₂ catalysts with a comparable hydrogen evolution catalytic performance in both acidic and alkaline environments is still an urgent challenge. Decreasing the energy barriers could enhance the catalysts' activity but is not often a strategy for doing so. Here, the first kinetic‐oriented design of the MoS₂‐based heterostructure is presented for pH‐universal hydrogen evolution catalysis by optimizing the electronic structure based on the simultaneous modulation of the 3d‐band‐offsets of Ni, Co, and Mo near the interface. Benefiting from this desirable electronic structure, the obtained MoS₂/CoNi₂S₄ catalyst achieves an ultralow overpotential of 78 and 81 mV at 10 mA cm^?2, and turnover frequency as high as 2.7 and 1.7 s^?1 at the overpotential of 200 mV in alkaline and acidic media, respectively. The MoS₂/CoNi₂S₄ catalyst represents one of the best hydrogen evolution reaction performing ones among MoS₂‐based catalysts reported to date in both alkaline and acidic environments, and equally important is the remarkable long‐term stability with negligible activity loss after maintaining at 10 mA cm^?2 for 48 h in both acid and base. This work highlights the potential to deeply understand and rationally design highly efficient pH‐universal electrocatalysts for future energy storage and delivery.     

Two-Way Cooperative Quantum Communication with Partial Entanglement Analysis

In this paper, we describe an improved cooperative two-way quantum communication scheme that works in a forward-and-backward fashion. In this scheme, partial entanglement analysis based on five-qubit entangled Brown state allows for the simultaneous exchange of arbitrary unknown states between Alice and Bob （with the help of trusted Charlie）. Security is guaranteed because opposing unknown states are transmitted by performing the suitable recovery operations in a deterministic way or, in the case of irregularities, no results are generated. The current two-way quantum communication scheme can also be extended to transmit arbitrary unknown states. This is done in a probabilistic way by using two-way quantum teleportation based on the generalized Brown-like state.     

光通信网物理层全光异或加解密技术研究

针对目前光通信保密系统中基于电信号处理的流密码加解密技术的局限性,提出基于全光信号处理的加解密技术;对几种典型的全光异或加密方案进行了研究,介绍了各自的工作原理、特点及研究进展;利用OptiSystem软件搭建了基于SOA-MZI(半导体光放大器-马赫-曾德干涉仪)异或门的全光加解密系统仿真模型,并基于HNLF(高非线性光纤)的自相位调制效应设计了一个优化结构对系统进行优化。研究表明:全光加解密技术具有优良的特性,能使整个光通信保密系统运算速率更高,传输更安全。     

TD-SCDMA系统业务分析功能的探讨及实现

本文在解码的基础上,结合协议统计功能,完成了TD-SCDMA系统业务分析功能的设计.此功能针对TD-SCDMA系统中接口协议栈的特点,从接口的信令中提取无线网络层中分别与无线资源管理有关的、与移动管理有关的和与呼叫管理有关的参数.对这些网络参数进行统计处理后,得到基站子系统的完备的统计数据.这些数据对制定无线网络资源优化措施提供数据支持,有利于解决网络优化工作中网络覆盖,信道拥塞,无线参数设置不合理等问题.     

基于小波变换的视频编码算法分类研究

在视频通信中,视频编码技术不但要有高的编码效率而且其生成的码流要有多种可伸缩性.在此研究领域.涌现出许多新的编码思想和技术,其中基于小波变换的视频编码算法就是很有发晨前景的技术之一.本文对小波变换视频编码算法进行分类研究.对比分析算法各自的优缺点,指出小波视频编码算法的研究方向.     

锥形图形衬底上氮化镓薄膜生长和表征

GaN films are grown on cone-shaped patterned sapphire substrates(CPSSs)by metal-organic chemical vapor deposition,and the influence of the temperature during the middle stage of GaN growth on the threading dislocation(TD)density of GaN is investigated.High-resolution X-ray diffraction(XRD)and cathodeluminescence(CL)wereusedtocharacterizetheGaNfilms.TheXRDresultsshowedthattheedge-typedislocation density of GaN grown on CPSS is remarkably reduced compared to that of GaN grown on conventional sapphire substrates(CSSs).Furthermore,whenthegrowthtemperatureinthemiddlestageofGaNgrownonCPSSdecreases,the full width at half maximum of the asymmetry(102)plane of GaN is reduced.This reduction is attributed to the enhancement of vertical growth in the middle stage with a more triangular-like shape and the bending of TDs.The CL intensity spatial mapping results also showed the superior optical properties of GaN grown on CPSS to those of GaN on CSS,and that the density of dark spots of GaN grown on CPSS induced by nonradiative recombination is reduced when the growth temperature in the middle stage decreases.     

超高斯脉冲反饱和吸收效应响应特性理论模拟

基于非线性传输方程与五能级速率方程的耦合模型分析了超高斯脉冲在反饱和吸收(RSA)作用下的动态响应特性。研究了脉冲时空波形在RSA材料中的演化规律以及脉冲与材料相互作用的动力学过程。讨论了单重态第一激发态寿命对输出脉冲时空波形的影响,并优化了材料参数以避免时空畸变。对新型RSA材料的开发以及在时空波形敏感领域的应用具有指导意义。